Automatic chord accompaniment for a guitar

In combination with a fretted musical instrument having a plurality of electrically conducting strings, apparatus for producing automatic accompaniment comprising;

• a clock providing timing signals,
• a string scanning means responsive to said timing signals wherein a string signal is created and is applied sequentially and cyclically to said plurality of electrically conducting strings,
• a string selection means interposed between said string scanning means and said plurality of electrically conducting strings whereby said string signal is applied to selected strings in said plurality of electrically conducting strings,
• fret circuitry whereby a fret signal is generated in response to said string signal when said selected strings are pressed into contact with frets on said fretted musical instrument,
• note decoding means responsive to said fret signals wherein a note number signal is generated,
• a status memory means for storing said note number signals,
• a first memory means for storing data to be thereafter read out,
• a transfer means whereby data is read from said status memory and stored in said first memory means,
• a second memory means for storing a plurality of transfer functions each corresponding to members of said preselected set of musical chord types,
• a correlation evaluation means responsive to selected members of said plurality of transfer functions and responsive to data accessed from said first memory wherein a plurality of correlation numbers are generated
• a third memory means wherein a correlation number is stored to be thereafter read out
• a comparison means for comparing the magnitude of each of said plurality of correlation numbers with the correlation number stored in said third memory means wherein a correlation number having the maximum value is selected and stored in said third memory means,
• a selection means responsive to said timing signals and said correlation number having a maximum magnitude value wherein a selection is made of a musical chord type from said preselected set of musical chord types,
• a root note detect means responsive to said selection of a musical chord type wherein a root note is selected,
• a note data generator means responsive to said selected musical chord type and said selected root note wherein input note data is generated, and
• a tone generator for creating musical tones at pitches responsive to said input note data.

A musical instrument having a plurality of tone generators for generating a plurality of tones and having a plurality of electrically conducting strings and frets for selecting musical notes comprising;

• a master clock means for generating a sequence of timing signals and a start signal corresponding to an initial timing signal,
• string scanning means responsive to said sequence of timing signals wherein said plurality of strings are scanned sequentially and cyclically,
• fret connection circuitry whereby said frets are connected in parallel octaves and wherein fret signals are generated in response to said scanned plurality of strings for fingered frets,
• string selection means for selecting fret signals corresponding to a preselected subset of strings from said plurality of electrically conducting strings,
• note decoding means responsive to said fret connection circuitry wherein note number signals are generated corresponding to said fret signals,
• a status memory for storing the state of said note numbers,
• a correlation memory means for storing data,
• a transfer means responsive to said start signal whereby data is transferred from said status memory to said correlation memory means,
• a transfer function memory means storing a plurality of matched filters each of which corresponds to a preselected musical chord type,
• a first memory addressing means responsive to said master clock means whereby each of said matched filters is selected consecutively from said transfer function memory means,
• a matched filter processor means wherein data stored in said correlation memory means is processed by each of said selected matched filters thereby generating a plurality of correlation numbers each of which corresponds to one of said selected matched filters,
• a decision means responsive to said plurality of correlation numbers wherein a selection is made of the matched filter corresponding to the maximum of said correlation numbers, and
• a utilization means responsive to said selection of a matched filter by said decision means wherein musical tones are generated.